1890.] NEW YORK ACADEMY OF SCIENCES. 143 



out ill a thin layer upon the more than usually hard basalt, hav- 

 ing been formed in seams instead of cavities. 



Some crystals of calcite in the form of dog-tooth and rhom- 

 bohedral spar are found, but most of them are imperfect. 

 Casts of calcite crystals, forming pseudomorphs by incrustation, 

 are not uncommon. 



Heulandite occurs in coffin-shaped crystals, some of them 

 quite large ; I have one over an inch in length. 



Datolite is found in fine, straw-colored crystals, and massive, 

 and in my specimens all deposited on the pseudomorphous 

 quartz. 



Stilbite is obtained in radiating tufts, and deposited upon the 

 crystals of quartz. 



Chabazite and analcite, in rose-colored crystals, are also 

 found; and some of the cavities of the amygdaloid contain natro- 

 lite. 



Of the copper minerals we have chalcocite and chalcopyrite, 

 and probably pseudomorphous after these, — malachite, azurite, 

 cuprite, and chrysocoUa. 



To recapitulate; — You have before you one hundred specimens 

 illustrating the product of this quarry. 



First the solid columnar basalt from the summit of the hill ; 

 basalt from the side of the hill next the falls, showing on one 

 side the action of the atmosphere and spray in decomposing the 

 surface, producing an efEect not unlike that shown in the spongy 

 amygdaloid when the cells are empty, but differing from it in 

 'that it is confined to the surface of the rock. 



You have the trap-rock from the quarry, brecciated with the 

 various copper minerals, which are seen to be still decomposing, 

 some of them crumbling since they have been in my possession. 



The hard, jaspery porphyrite; the amygdaloid, a spongy mass 

 of cavities, some of which are filled, and others from near the 

 surface, where they have been exposed to the elements, empty, 

 resembling spongy scoriae. 



The normal pectolite in silky fibres and numerous stages of 

 the change to silica or prehnite. 



The normal prehnite in reniform and botryoidal masses. One 

 specimen shown, from the D., L. & W. E. R. cut on the other 

 side of the river, half a mile away (collected several years ago), 

 differs from that found in this quarry only in being lighter col- 

 ored ; we see. too, the fan-like pectolite forms in beautiful ra- 

 diations of green prehnite. 



The normal calcite crystals, which are neither abundant nor 

 fine ; but silica pseudomorphs by incrustation after calcite, the 

 included mineral having been dissolved away, are plentiful, 

 showing that the more soluble mineral was once quite abundant. 



